Technical Field
The present disclosure generally relates to the manufacturing and testing of integrated circuits (ICs).
Description of the Related Art
A ring oscillator is a device that includes an odd number of inverting elements (e.g., inverters, NAND gates, NOR gates, etc.) in a ring, whose output oscillates between two voltage levels. The inverting elements are connected as a chain. Signals propagate through the chain of inverting elements and the output of the last inverting element is fed back into the first. Many wafers include a ring oscillator as part of the scribe line test structures. They are used during wafer testing to measure the effects of manufacturing process variations. Ring oscillators can also be used to measure the effects of voltage and temperature on an IC.